As is well known, the operation of an internal combustion engine produces waste heat as well as mechanical energy. Liquid coolant systems are typically provided to remove this waste heat from the internal combustion engine to reduce operating temperature and to extend the life of mechanical parts and lubricants.
It is known to provide coolant reservoir tanks on liquid cooling systems, particularly cooling systems for internal combustion engines. Such reservoir tanks provide a surplus supply of coolant in reserve to compensate for inevitable minor leaks and evaporation. Coolant reservoir tanks additionally provide surge capacity for the storage of liquid coolant during engine operation. The volume of liquid coolants varies in relation to changes in coolant temperature. As the engine warms the coolant typically expands in volume. In such cases the coolant reservoir provides fluid storage capacity to accommodate this coolant surge while keeping it ready to return back to the coolant system when engine operation ceases. As can be seen, coolant necessarily flows between the coolant reservoir and the remaining coolant system due to changes in operating conditions of the engine, such as operating temperature changes and engine start/stop transitions.
During engine operation particulate contaminants may become entrained into the coolant. Such particulate contaminants may include, for example, rust or scale from coolant passages in the engine, dissolved minerals which may precipitate from the coolant, contaminants formed from chemical reactions between various fluid and engine system components, gasket materials, metallic and plastic debris resulting from mechanical wear of rotating or moving components into which the coolant comes into contact, as well as other causes.
It is well known that contaminants and debris, if not removed from the coolant, can accumulate upon the walls of engine and radiator system coolant passageways and thereby reduce the amount of heat transferred between engine/radiator components and the coolant. In an effort to address the coolant contaminant problem, several solutions have been developed.
In U.S. Pat. No. 3,726,262, a cooling system for an internal combustion engine includes a degassing line between the engine and coolant reservoir tank. A disposable filter is provided in the degassing line to filter coolant transitioning between the coolant system and the reservoir. The filter housing and filter element are not integrated internally into the coolant reservoir, and the solution is unnecessarily complex to manufacture and therefore unnecessarily costly.
Another solution is provided by U.S. Pat. No. 5,753,116 which discloses a separate coolant filter assembly for an engine coolant system.
Another coolant filtering solution is taught by PCT Publication number WO 00/06874. A coolant system for an internal combustion engine is disclosed including a radiator, a pump to circulate the coolant, a thermostatically operated bypass valve and a coolant reservoir equipped with a removable pleated cartridge assembly. The filter cartridge assembly is unnecessarily complex in materials and construction, resulting in an unnecessary higher cost and complex solution.
As can be seen, there is a need for an integrated filter system for a coolant reservoir tank that is simple in construction, low in cost, is easily replaced, and overcomes limitations of the prior art.